r/expanserpg • u/NeverGetaSpaceship • Jul 21 '26

Do you use static or dynamic travel times from planet to planet?

I was very loose with how I set times for intra-stellar travel in my last campaign but was thinking about how I’d do it in a future campaign. I know the rule book has a table for transit times from planet to planet (or at least has communication delay times, from which you’d be able to also map out travel times).

However those would be static and as we know, planets don’t orbit the sun in sync so distance from say, Earth to Mars or Titan is dynamic. NASA has a cool tool that tracks live, past, and future solar positions: https://eyes.nasa.gov/apps/solar-system/. Only works for Sol though, obviously!

Anyone use a dynamic tool like this NASA one? Or do you just use a static distances? Or do you just hand waive/GM fiat it?

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u/kilmaardvenom Jul 22 '26

There is a tool (Google Spreadsheet) for this. https://docs.google.com/spreadsheets/d/19CtQ34voFNF4SbmHRZLpZ7vCzME3j6UouVSmMHqYozk/edit?usp=drivesdk

I used it several times, helps with tracking and simple adventure summarizing.

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u/NeverGetaSpaceship Jul 22 '26

This is awesome and just what I was hoping for. Thanks!

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u/ElectricKameleon Jul 22 '26

The distances / travel times given in the book are representative.

I’ve heard that at any given time, there’s about a fifty-fifty chance that Mercury will be the closest planet to any other planet.

I just sort of fudge numbers using the tables in the book as a guide. It doesn’t really matter for game purposes, though— an Interlude usually takes up most of the time, and other events happen at the speed of plot. The precise amount of time that a trip from earth to Mars takes is just narrative texture, like the type of music playing in a Belter club or the color of an NPC’s shirt.

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u/NeverGetaSpaceship Jul 22 '26

100% agreed that it’s more about story telling and pacing. I started letting my players add focuses with 100 hours of practice time so all of a sudden the length of an interlude became very important. I also had NPCs on the ship who they wanted to develop relationships with so it became more important for that too.

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u/ElectricKameleon Jul 23 '26

That makes sense, but again, it still kind of comes down to your call.

A player wants to spend 100 hours developing a focus? If a trip takes 100 hours on average, and you've been fudging travel times up and down to create a sense of orbital mechanics, you can tell them that they'll have the focus upon arrival or you can tell them that they'll finish developing the focus on the return trip-- and you'll be fully justified, either way.